Field of the Invention
The present invention relates to an ink jet recording sheet which has excellent ink retention properties, color development properties, weather resistance and water resistance, and which is substantially free from curling even if it has its only one side provided with an ink receiving layer. In particular, the present invention relates to an ink jet recording sheet which is extremely suited for use in poster applications.
2. Description of the Prior Art
Hitherto known recording methods include a thermal mass transfer recording method, a thermal sublimable dye transfer recording method, an electrophotographic recording method, and an ink jet recording method. Of these, the ink jet recording method has increasingly employed in recent years in view of noiselessness in recording operation, high speed operation, suitability for recording a large graphic, economically desirable running cost therefor. Recently, increasing requests have been made to prepare large-sized posters, signs or the like in a lot having a small size in full color in a short appointed period of time. In addition to the above-mentioned desired properties, the ink jet recording method has an advantage that it is readily adaptable for recording in multicolor. Accordingly, the ink jet recording method is suited to meet such requests.
The ink jet recording method fully exhibits its excellent effect by means of a combination of an ink jet printer with a recording sheet suitable for the printer. However, as improvements have been made in performance of an ink jet printer as the fruits of technological progress, ink jet recording sheets have been desired which have excellent properties commensurate with the improvements.
In particular, an ink jet recording sheet has been desired which exhibits a color development density that is high enough for use in a large-sized poster or the like, and which enables formation of a clear graphic substantially free from graphic irregularity and color irregularity, and which is less susceptible to deterioration of a graphic formed even if exposed to sunlight, UV-containing light or the like, and which has excellent water resistance.
In the existing circumstances, however, an ink jet recording sheet has not yet been provided which has excellent properties as described above. Only recording sheets which are described in the following and such like have been proposed.
For example, as a conventional ink jet recording sheet, an ink jet recording sheet is proposed in Japanese Unexamined Patent Publication No. 189480/1985 which comprises a substrate, and an ink receiving layer provided thereon and including a filler (such as synthetic silica, magnesium carbonate, calcium silicate or the like) and a polymeric binder.
In the ink jet recording sheet according to the proposal, however, a colorant is retained only by adsorption thereof on the filler. Accordingly, the recording sheet has a problem that retention of the colorant in the ink receiving layer is poor and, in particular, the colorant is likely to bleed when the recording sheet is wetted.
In Japanese Unexamined Patent Publication No. 57379/1986, an ink jet recording sheet is proposed which is provided with an ink receiving layer containing therein a cationic resin.
The ink jet recording sheet according to the latter proposal has colorant retaining mechanism different from that of the ink jet recording sheet according to the former proposal. In the ink jet recording sheet according to the latter proposal, cationic groups in the ink receiving layer react with anionic groups of a colorant of an ink, such as SO.sub.3 .sup.--, COO.sup.- or the like to form water-insoluble salt, Accordingly, retention of the colorant is improved, leading to improved water resistance of the colorant. On the other hand, however, the recording sheet according to the latter proposal has a problem that its weather resistance is poor.